The Ecological Crunch and the Dyer Scale

When I saw the headline, “50 percent of all species disappearing”[2, 3, 4, 5, 6, 7, 8, 9] my first thought was of the Dyer scale. In his 2004 book, Future Tense, Gwynne Dyer defines a logarithmic scale of disasters in order to get a sense of proportion about terrorism. The idea can be applied more generally.

Here is how he defines it:

“If we are ever to get some sense of proportion back about terrorism, we need a logarithmic scale for disasters like the one they use for stars. Only the very brightest stars are First Magnitude; divide the brilliance by ten for Second Magnitude stars, by a hundred for Third Magnitude, and so on. Ranking human disasters by the same system, only those that could kill, say, half the population in question would be First Magnitude. For the twelve million Jews who lived in Europe in 1939, the Holocaust was a First Magnitude calamity; half of them were dead by 1945. At the global level, a First Magnitude disaster would be one that killed around three billion people: it is possible to imagine a return of the Black Death, for example, that would kill three billion people, and an all-out global nuclear war could reach the same casualty level.”

“Divide by ten and a Second Magnitude global disaster is one that kills in the low hundreds of millions of people. A ‘clean’ Third World War with relative restraint in the nuclear targeting of cities and no nuclear-winter effect would fall into this range. The AIDS epidemic may ultimately prove to be a Second Magnitude disaster, although a very slow moving one. Divide by ten again and we are down to Third Magnitude disaster like the First and Second World Wars and the Spanish Influenza outbreak of 1918-19, which all killed 10 to 50 million people. An Indo-Pakistani nuclear war would be a Third Magnitude disaster, as would an Israeli decision to unleash its nuclear arsenal on its Arab neighbours.”

“Divide by ten once more, and we are down to Fourth Magnitude events, only one-thousandth as big as First Magnitude ones. Big or long-lasting local wars like Korea 1950-53, Vietnam 1965-73, and Sudan 1983-2003 fall into this range, killing two or three million people. The slaughter in the Great Lakes region of Africa that began the Rwanda genocide of 1994 and continues today in Eastern Congo probably qualifies by now as a Fourth Magnitude event. An out-of-control nuclear meltdown in a densely populated area or a megaton-range bomb exploded at the right height over a very large city could also cause deaths at a Fourth Magnitude level.”

“Divide by ten again and we drop to the level of purely local catastrophes like the Lisbon earthquake of 1755, the Krakatoa explosion of 1883, the atomic bombing of Hiroshima in 1945, and wars in former Yugoslavia in the 1990s, each of which killed in the quarter-million range. Potential Fifth Magnitude calamities in the present include the Big One along the San Andreas fault in California, an average year’s famine toll in Ethiopia, or a successful terrorist attack on a major city using a ground-burst nuclear weapon.”

“Another division by ten, and we drop to Sixth Magnitude events like the war in Iraq in 2003, the 2004 earthquake in Iran, and the Arab-Israeli War of 1967, all of which caused 20,000 to 50,000 fatal casualties. Worse case scenarios for highly successful terrorist attacks using biological weapons very rarely rise above this level. And a final division by ten brings us down to Seventh Magnitude events like the IRA’s war in Northern Ireland from 1969 to 1998, the Second Intifada in Israel/Palestine from 2000 to the present, and the 9/11 attacks on the United States in 2001, all of which have caused on the order of three thousand deaths. About as many Americans die each month from gunshot wounds as died in the Twin Towers, the Pentagon and Flight 93, and those losses, unlike the terrorist attacks, recur every month. So why is terrorism regarded by both the U.S. government and media as the world’s number-one problem?” Future Tense, pages 53-55

One might quibble with a few details. eg. Why is the first step binary, not decimal? Why is extinction undefined (Level Zero)? Why are the exponents and the resulting magnitudes reversed? But the general idea is still useful as an antidote to unthinking emotionalism. We are talking about terrible things, and that makes it all the more incumbent upon us to think clearly.

Although one could try to apply such a schema to whole ecologies, the more intuitive and straightforward application would be to individual species. This quickly turns into a knot of details [How many species are there? What species do we need to consider? Bacteria? How many members of each species are there? What point in time do we select to begin our population tally? eg. American buffalo as of 1900 or 1800?] for which the RedListis most useful.

I regret needing to say it, but as the century unfolds and we slide into the ecological crunch, the Dyer Scale or a similar logarithmic scalewill be useful in keeping perspective.

2008/10/06: BBC: Mammals facing extinction threatAt least 25% of the world’s mammal species are at risk of extinction, according to the first assessment of their status for a decade. The Red List of Threatened Species says populations of more than half of mammalian species are falling, with Asian primates particularly at risk. The biggest threat to mammals is loss of habitat, including deforestation.

2008/10/06: CBC: 1 in 4 mammals threatened with extinction: reportThe first review of the world’s mammals in more than a decade paints a bleak picture, with close to a quarter of species threatened with extinction, according to the International Union for Conservation of Nature. The main threats are habitat loss and overexploitation for terrestrial mammals, and pollution, global warming and overexploitation for marine mammals, according to the authors of a study to be published Friday in the journal Science.

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L. F. Richardson, whom climate folks know for inventing numerical weather prediction, turned to war in his later life. In his Statistics of Deadly Quarrels he used a logarithmic (base 10) scale for discussing the magnitudes of the quarrels. Magnitude 7.5 was, then, an event which killed around 30 million people.

One of the remarkable things he found was that there was a relation between the magnitude of the quarrels and their frequency.

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